Coggeshall slide rule

In measurement, the Coggeshall slide rule, also called a carpenter's slide rule, was a slide rule designed by Henry Coggeshall in 1677 to facilitate measuring the dimensions, superficies, and solidity of timber. With his original design and later improvements, Coggeshall's slide rule brought the tool its first practical use outside of mathematical study. It would remain popular for the next few centuries.^[1]

It consisted of two rulers, each a foot (30 cm) long, which were framed, or put together, in various ways. Sometimes, they were made to slide by one another; sometimes, a groove was made in the side of a common two-foot joint-rule, and a thin sliding piece was inserted, with Coggeshall's lines added on that side; but the most usual and handy way, was to have one of the rulers slide along a groove made along the middle of the other, as shown in the figure below.^[2]

Coggeshall first described this apparatus in a paper he released in London titled, "Timber-measure by a line of more ease, dispatch and exactness, then any other way now in use, by a double scale : after the countrey-measure, by the length and quarter of the circumference in round timber, and by the length and side of the square in squared timber, and square equal in flat timber : as also stone-measure and gauging of vessels by the same near and exact way, likewise a diagonal scale of 100 parts in a quarter of an inch, very easy both to make and use."^[3]

After improving the design, he republished his work under the title "A Treatise of Measuring by a Two-foot Rule, which slides to a Foot" (1682). He released a highly modified version in 1722 titled "The Art of Practical Measuring easily performed by a Two-foot Rule which slides to a Foot." By 1767, seven revised editions had been released.^[3]

References

1. ^ Slide Rule History. The Oughtred Society. URL accessed 2006-06-09
2. ^  This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.
3. ^ ^{a b} Cajori, Florian. History of the Logarithmic Sliding Rule." Colorado College. 1909. URL accessed 2006-06-10.